Chinese patent application No. 201220287142.7 discloses an oval electronic cigarette, aiming to provide an electronic cigarette with a mouthpiece of vaporizer, a copper part and a vaporization rod all can be demounted, and therefore the oval electronic cigarette is convenient to carry and replace. The technical solution is as below. The oval electronic cigarette is composed of a battery portion, an oil storage portion, a vaporization portion and a mouthpiece portion, wherein an oval battery is arranged in the battery portion, the oil storage portion comprises a transparent casing, the vaporization portion comprises a vaporizer arranged in the oil storage portion, and the mouthpiece portion comprises a plastic mouthpiece according with the food level standard and is arranged at the top end of the electronic cigarette. The oval electronic cigarette has disadvantages as follows. Since the vaporizer of the oval electronic cigarette is arranged inside the oil storage portion at the proximal end of the mouthpiece, the gas vaporized under high temperature may directly get to smoker's mouth and consequently the risk of mouth burning is high. In addition, after vaporization, the vapor flow channel is too short, so that impurities and steam cannot be completely separated and will lead to undesired taste. Moreover, the vaporizer, the copper part and the vaporization rod need to be demounted many times and it is not convenient for the user to use.